418 



BOTANY 



neck, whose upper cells become disorganised on opening. The pro- 

 thallium of L. Phlegmaria, found on trees in the tropics, is also sapro- 

 phytic. It consists of branching strands growing under the bark of 

 trees, and is characterised by the possession of a vegetative mode 

 of propagation by means of brood -tubers. The prothallia of the 



Fig. 350. — Lycopodium cernuum. A, Prothallium with two archegonia ar, and an antheridium 

 an (x 70) ; B, older prothallium, p, with embryonic plants ( X 15) ; C, section through an 

 antheridium ( x 250) ; D, archegonium ; o, egg-cell ; bo, ventral canal-cell ; he, disorganised neck- 

 canal-cell. (After Teeub, x 250.) 



Lycopodiums are monoecious. The embryonic development, which is 

 effected differently from that in the Ferns, agrees closely with that of 

 Selaginella (Fig. 355). A suspensor or embryo-bearer is developed ; 

 it is not, however, laterally inserted, but occurs on the contrary at 

 the foot end of the embryo. 



Officinal. — (Lycopodium), the spores of Lycopodium clavatum and 

 other species. 



Order 2. Selaginellaeeae 



To this order belongs the genus Selaginella, represented by numerous 

 and for the most part tropical species. They have, as a rule, profusely 

 forked, creeping, and sympodially branched stems, but occasionally 

 erect, branched stems ; some form moss-like beds of vegetation ; others, 

 climbing on adjacent plants, possess stems several metres long. In 

 general the Selaginellas are similar in habit to the Lycopodiums. 

 They have small, scale -like leaves which usually exhibit a dorsi- 

 ventral arrangement, such as is shown, for example, in the Alpine 



